I actually disagree that we'd no longer perform R&D or build new things. Rather, there would be a significant increase in retrofits to existing equipment. For example even cars from 30 years ago used standard DIN slots with DIN rails to mount their stereo equipment. You could easily build something to replace that equipment and retrofit in-dash GPS. And replacing the HVAC and retrofitting AC onto old engines is also possible by modifying the serpentine belt routing and cutting holes in the firewall.

Almost certainly what would happen is manufacturers would build more robust things and there would be more "ships of theseus" where you're running a 30-year old cabinet but with modern materials and components. People would generally have to be more technical and develop more one-off solutions.